This invention relates to an exposure apparatus and exposure method ideal for manufacturing a semiconductor device, a discharge lamp employed as a light source in the apparatus, and a method of manufacturing a device using the exposure apparatus.
An optical unit in an exposure apparatus used to manufacture a semiconductor device has an illuminating optical unit for illuminating a reticle, which possesses a pattern, with exposing light, and a projection optical unit for projecting and imaging the reticle pattern on a wafer substrate. The illuminating optical unit is equipped with a light source that produces the exposing light, and a mercury-vapor lamp (discharge lamp) for generating i line-light or g line light is used widely as the exposing light source.
Since a high-output discharge lamp used in an exposure apparatus has a short life, it is required that the lamp be replaced periodically depending upon the operating time of the exposure apparatus. For this reason, the light source is provided with a holder, such as a socket, for holding the discharge lamp in a removable manner in order to facilitate replacement.
A variety of improvements have resulted in the recent development of discharge lamps having various capabilities and there has been an increase in the types thereof available.
Because discharge lamps have not been strictly standardized, the specifications thereof differ from maker to maker and lamp characteristics differ slightly depending upon the type. Examples of differences in characteristics include disparities in optimum cooling conditions, allowable power range and the shape of the minute arc (arc shape at the light-emitting point of the lamp) produced. Though no problems arise if a discharge lamp intended for the exposure apparatus is used, when making a replacement, but there are instances where replacing an old discharge lamp with a new discharge lamp of a different type results in a mismatch of characteristics.
Though it may be possible to have a maintenance expert check the type of discharge lamp and set newly optimum conditions suited to the discharge lamp, making such setting whenever a discharge lamp is replaced is troublesome and leads to increased servicing labor. Moreover, if the person performing such maintenance misidentifies the type of discharge lamp and makes the wrong setting, the exposure apparatus may operate with the wrong characteristics and fail to manifest the desired exposure performance.
For example, assume that a discharge lamp is not subjected to optimum cooling. If the lamp is cooled excessively, difficulties such as failure to obtain the desired spectral power may occur. Additionally, if the discharge lamp is cooled inadequately, its temperature will rise and this can seriously shorten the life of the discharge. Further, if power in excess of the maximum allowable power of the discharge lamp is applied thereto owing to an erroneous setting, this can shorten the life of the device (discharge lamp). If the shape of the arc of the discharge lamp does not match the hypothetical design value of the illuminating optical unit, this can result in failure to obtain the desired illuminating light on the reticle and cause a decline in exposure transfer precision.
Accordingly, a prime object of the present invention is to provide an exposure apparatus and a method capable of flexibly supporting discharge lamps of a variety of different types.
Another object of the present invention is to provide a discharge lamp that can be adapted to an exposure apparatus mentioned above.
A more specific object of the present invention is to provide an exposure apparatus and method in which it is possible to identify the type of discharge lamp and identifies settings suited to the discharge lamp, as well as a discharge lamp that makes this possible.
A further object of the present invention is to provide an outstanding device manufacturing method that uses the exposure apparatus mentioned above.
According to the present invention, the foregoing objects are attained by providing an exposure apparatus and a method, a device manufacturing method using this exposure apparatus, and a discharge lamp constructed as set forth below.
Specifically, the present invention provides an exposure apparatus using a discharge lamp as a light source, the exposure apparatus having a sensor for recognizing the type of discharge lamp mounted in a holder or recognizing whether a discharge lamp has been mounted in the holder.
Alternatively, the present invention provides an exposure apparatus using a discharge lamp as a light source, the exposure apparatus having means for setting at least one of optical conditions, power source conditions and cooling conditions in dependence upon the type of discharge lamp mounted.
Further, the present invention provides a device manufacturing method using the exposure apparatus which includes steps of preparing the exposure apparatus and performing exposure using the exposure apparatus.
Further, the present invention provides an exposure method using a discharge lamp as a light source, the exposure method including steps of recognizing the type of discharge lamp and automatically setting at least one of optical conditions, power source conditions and cooling conditions based upon the recognition made.
Further, the present invention provides a discharge lamp used as a light-emitting source of a light source device, the discharge lamp having a mark or shape capable of being recognized by a sensor when the discharge lamp is used in the device.
In accordance with a preferred embodiment of the present invention, the exposure apparatus further includes means for setting at least one of optical conditions, power-source conditions and cooling conditions, which conform to the type of discharge lamp mounted, based upon the recognition made.
In accordance with a preferred embodiment of the present invention, the exposure apparatus further includes means for changing optical conditions of an optical illuminating unit in dependence upon the type of discharge lamp.
In accordance with a preferred embodiment of the present invention, the exposure apparatus changes the optical conditions by adjusting a zoom lens of the illuminating optical unit in accordance with the type of discharge lamp.
In accordance with a preferred embodiment of the present invention, adjusting the zoom lens optimizes the shape of the image of an arc produced by the discharge lamp.
In accordance with a preferred embodiment of the present invention, the exposure apparatus further includes means for changing the power-source conditions by setting allowable power applied to the discharge lamp in dependence upon the type of discharge lamp.
In accordance with a preferred embodiment of the present invention, the exposure apparatus further includes means for changing discharge-lamp cooling performance in dependence upon the type of discharge lamp.
In accordance with a preferred embodiment of the present invention, the exposure apparatus further includes means for cooling the mounted discharge lamp by a gas.
In accordance with a preferred embodiment of the present invention, a sensor is provided in the vicinity of the holder and senses a characterizing portion formed on the discharge lamp held by the holder.
In accordance with a preferred embodiment of the present invention, the sensor of the exposure apparatus senses the characterizing portion optically, magnetically, mechanically or through use of pressure.
In accordance with a preferred embodiment of the present invention, the characterizing portion is a groove or hole formed in the discharge lamp in the vicinity of a location at which the discharge lamp is held by the holder.
In accordance with a preferred embodiment of the present invention, the exposure apparatus further includes means for allowing an operator to input the type of discharge lamp mounted or for recognizing the type of discharge lamp automatically.
In accordance with a preferred embodiment of the present invention, the exposure apparatus further includes memory means for storing types of discharge lamps and setting conditions suited thereto, wherein optical conditions, power source conditions and cooling conditions conforming to the type of mounted discharge lamp are set based upon content of the memory means.
In accordance with a preferred embodiment of the present invention, the exposure apparatus further includes means for changing optical conditions of an illuminating optical unit in dependence upon the type of discharge lamp.
In accordance with a preferred embodiment of the present invention, the exposure apparatus changes the optical conditions by adjusting a zoom lens of the illuminating optical unit in accordance with the type of discharge lamp.
In accordance with a preferred embodiment of the present invention, adjusting the zoom lens by the exposure apparatus optimizes the shape of the image of an arc produced by the discharge lamp.
In accordance with a preferred embodiment of the present invention, the exposure apparatus further includes means for changing the power source conditions by setting allowable power applied to the discharge lamp in dependence upon the type of discharge lamp.
In accordance with a preferred embodiment of the present invention, the exposure apparatus further includes means for changing discharge-lamp cooling performance in dependence upon the type of discharge lamp.
In accordance with a preferred embodiment of the present invention, the exposure apparatus further includes means for cooling the mounted discharge lamp by a gas.
In accordance with a preferred embodiment of the present invention, the exposure apparatus further includes means for inhibiting firing of the discharge lamp and/or for issuing a warning in a case where the type of discharge lamp cannot be recognized.
In accordance with a preferred embodiment of the present invention, the exposure apparatus further includes means for inhibiting application of voltage and/or for issuing a warning in a case where a discharge lamp has not been mounted in a mounting portion.
In accordance with a preferred embodiment of the present invention, the exposure method further includes a step of inhibiting firing of the discharge lamp and/or issuing a warning in a case where the type of discharge lamp cannot be recognized.
In accordance with a preferred embodiment of the present invention, the exposure method further includes a step of sensing whether a discharge lamp has been mounted and inhibiting firing of the discharge lamp and/or issuing a warning in a case where a discharge lamp has not been mounted.
In accordance with a preferred embodiment of the present invention, a discharge lamp used as the light source of the exposure apparatus has a mark or shape capable of being recognized by a sensor when the discharge lamp is used in an exposure apparatus.
In accordance with a preferred embodiment of the present invention, the discharge lamp used as the light source of an exposure apparatus uses any of a three-dimensional shape, planar shape, pattern, coloring, reflectivity and audio as the mark or shape.
In accordance with a preferred embodiment of the present invention, the discharge lamp used as the light source of the exposure apparatus is formed to have a groove or hole capable of being sensed by a sensor provided in the vicinity of a holder of the discharge lamp.
In accordance with a preferred embodiment of the present invention, the mark or shape which the discharge lamp uses is provided to achieve a plurality of applications.
In accordance with a preferred embodiment of the present invention, the plurality of applications are identifying the type of discharge lamp, identifying whether a discharge lamp is mounted or not, or cooling the discharge lamp.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.